Caudate nucleus dopamine (DA) D2 receptors were studied in patients with vascular dementia (VaD) and in a control group using [3H]raclopride as a radioligand. There was no significant difference in the number of DA D2 receptors in the VaD group as compared with controls. The binding affinity was significantly lower in the VaD group. When the VaD group was subdivided into subjects with or without neuroleptic treatment, there were no differences in the numbers of receptors as compared with controls, and the significant differences in binding affinity remained for both VaD subgroups. The present results are discussed with reference to the previous finding of a reduced density of caudate nucleus DA uptake sites in the same VaD group and to results from studies on DA D2 receptors in Alzheimer's disease and Parkinson's disease. Copyright ⌐ 2002 S. Karger AG, Basel.

The binding of [H-3]tiagabine ((RS-1-(4,4-(3-methyl-2-thienyl)-3-butenyl)-3 carboxylic acid) to homogenates of frozen post-mortem human brain has been characterized. Inhibition experiments with gamma-aminobutyric acid (GAB,4), GABA uptake inhibitors, ligands active at postsynaptic GABA receptors and receptors for other neurotransmitters, suggest that [H-3]tiagabine binds with high affinity to GABA uptake sites. Inhibition and kinetic experiments suggests that 70%-80% of the binding is to a high affinity site. Saturation experiments showed that the binding was saturable. B-max was 3.4 pmol/mg protein and K-d 16 nM in frontal cortex. The dissociation constants (K-d) measured in kinetic and equilibrium experiments were in the same range (16-56 nM). The regional distribution was studied in nine brain regions and the binding was heterogenous, with the highest binding in frontal cortex and parietal cortex and the lowest binding in nucleus caudatus and putamen. This is, to our knowledge, the first study on [H-3]tiagabine binding in human tissue. It is concluded that [H-3]tiagabine binding can be used as a specific marker for the GABA transporter GAT-1 in homogenates of human brain.

Alzheimer disease (AD) treatment guidelines state that cholinergic agents are not cost-effective in patients with more severe disease. Because many physicians may deem an older patient unlikely to respond to treatment, older AD patients may remain untreated. Galantamine (Reminyl), a novel cholinergic agent, is effective in mild to moderate AD. This post hoc analysis of pooled phase III galantamine clinical trials was designed to assess whether older (=80 years) and younger (=79 years) AD patients experience similar benefits with galantamine based on changes in the ADAS-cog and CIBIC-plus. Mean ADAS-cog scores for older patients treated with galantamine 24 mg/day significantly improved versus baseline and versus placebo at month 3. Cognitive improvement was maintained versus placebo at month 6, the ADAS-cog score for placebo patients dropped below baseline at month 6. Change in CIBIC-plus for galantamine was significantly different from placebo at months 5 to 6. Mean ADAS-cog score in older patients taking galantamine for 12 months remained above baseline. The score for patients taking placebo for 6 months before switching to galantamine did not differ significantly from baseline at 12 months but was lower than in patients receiving galantamine for 12 months. Incidence of adverse events in patients > 80 years was similar to that in the overall study population. Galantamine maintained cognitive and global function in patients > 80 years with mild to moderate AD for at least 5 to 6 months and cognitive efficacy for 12 months. Prescribing approved therapies such as galantamine for older patients with AD is recommended.

A polymorphism consisting of a deletion near the 5' splice site of exon 18 on the a2-macroglobulin (A2M) gene (A2M-2) has been suggested to be associated with Alzheimer's disease (AD) in family-based studies. We studied the A2M-2 allele together with the ApoE alleles in a large series on patients with AD (n = 449) and age-matched controls (n = 349). Neuropathologically confirmed diagnoses were available in 199 cases (94 AD and 107 control cases). We found no increase in A2M-2 genotype or allele frequencies in AD (27.5% and 14.6%) versus controls (26.4% and 14.9%). In contrast, a marked increase (p < 0.0001) in ApoE e4 genotype or allele frequencies was found in AD (66.6% and 41.2%) as compared with controls (29.8% and 16.5%), suggesting sufficient statistical power in our sample. No relation was found between the A2M-2 and the ApoE e4 allele. No change in A2M exon 17-18mRNA size or sequence or A2M protein size was found in cases carrying the A2M-2 deletion, suggesting that there is no biological consequences of the A2M intronic deletion. No change in A2M protein level in cerebrospinal fluid was found in AD, suggesting that the A2M-2 allele does not effect the A2M protein expression in the brain. The lack of an association between the A2M-2 allele and AD in the present study, and the lack of abnormalities in the A2M mRNA or protein suggest that the A2M-2 allele is not associated with AD.

Linköping University, Faculty of Health Sciences. Linköping University, Department of Department of Health and Society, Division of Preventive and Social Medicine and Public Health Science. Östergötlands Läns Landsting, Centre for Public Health Sciences, Centre for Public Health Sciences.

The presynaptically located gamma-aminobutyric acid (GABA) transporter (GAT-1) was studied in a group of patients with Alzheimer's disease (AD) and in a control group using the GAT-1 selective radioligand [H-3]tiagabine. Post mortem brain tissue from frontal cortex, temporal cortex, and caudate nucleus from 18 AD patients and 23 age-matched controls were studied. The binding was saturable (Kd 26 nM) and region specific. There were no significant differences between the groups with respect to the binding capacity (Bmax) and binding affinity (Kd). The unaltered [H-3]tiagabine binding to GAT-1 protein indicates that intrinsic GABA neurons are spared in Alzheimer's disease.

Background - Pathological tau protein concentrations in CSF are found in both Alzheimer's disease (AD) and frontotemporal dementia (FTD), but studies on brain tissue have suggested that the tau pathology in AD differs from that in FTD and that the difference may be related to the degree of phosphorylation. As CSF tau protein is increased after stroke, tau may also be implicated in the pathophysiology of vascular dementia, of which subcortical arteriosclerotic encephalopathy (SAE) is a putative subtype. Objectives - To investigate the nature of tau protein in CSF and the involvement of total CSF tau and phosphorylated CSF tau (phosphotau) in various types of dementia. Methods - Using ELISAs for total tau and tau phosphorylated at Thr181 (phosphotau), the CSF concentrations of total tau and phosphotau were determined in patients with probable and possible AD (n=41 and 19, respectively), FTD (n=18), SAE (n=17), and Parkinson's disease (PD, n= 15) and in age matched controls (n=17). All the antibodies stained the lower molecular weight bands, whereas only the antibodies that recognise phosphorylated tau stained the higher molecular bands. Results - Both CSF tau and CSF phosphotau were increased in probable AD compared with FTD (p<0.001), SAE (p<0.001), PD (p<0.001), and controls (p<0.001). CSF phosphotau was increased in possible AD compared with FTD (p<0.001) and SAE (p<0.001). CSF tau and CSF phosphotau were positively correlated in all the groups. Molecular weight forms of tau ranging from 25 kDa to 80 kDa were found in the CSF Conclusion - Both phosphorylated and unphosphorylated tau isoforms were present in the CSF, and tau protein appeared in both truncated and full length forms. The results suggest that the CSF concentrations of tau and phosphotau are increased in about two thirds of patients with probable AD and in half of those with possible AD but are normal in FTD, SAE, and PD compared with normal aging. Values in the normal range do not exclude AD.

Cerebrospinal fluid (CSF) levels of tau, ▀-amyloid1-42 and growth-associated protein 43 (GAP-43) were studied in patients with frontotemporal dementia (FTD, n = 17), Alzheimer's disease (AD, n = 60), subcortical white-matter dementia (SWD, n = 24), Parkinson's disease (PD, n = 23) and dysthymia (n = 19) and in age-matched controls (n = 32). CSF-tau was significantly increased only in AD, and CSF-▀-amyloid1-42 was significantly decreased in AD and SWD as compared to controls, and in AD compared to FTD. CSF-GAP-43 was significantly decreased only in PD. The GAP-43/tau ratio was decreased in all the patient groups except the dysthymia group compared to controls. A positive correlation was found between CSF-GAP-43 and CSF-tau in all groups. The results suggest normal levels of CSF-tau and CSF-▀-amyloid1-42 in FTD, which will aid in the clinical separation of FTD from AD. In SWD, decreased levels of CSF-▀-amyloid1-42 suggest concomitant involvement of vascular and amyloid protein mechanisms.

Olanzapine (Zyprexa«) was approved for general prescription in Sweden in November 1996, and an HPLC-based therapeutic drug monitoring (TDM) routine for serum olanzapine (OLA) and its major metabolite, N-demethylolanzapine (DMO) was established in February 1997. During 1997 to 1999, a total of 753 TDM requests for a total of 545 Swedish patients was analyzed. Additional patient information on certain clinical variables was collected on specifically designed TDM request forms. After the exclusion process, samples from 194 patients were found to be eligible for further scrutiny. The concentration-to-dose (C/D) ratio for OLA varied 25-fold and that of DMO 22-fold. Women had a higher (P < 0.01) median C/D ratio for OLA than men (median, 7.2 nmol/L/mg vs 5.2 nmol/L/mg). Nonsmokers had a higher (P < 0.001) C/D ratio for OLA than smokers (median, 9,2 nmol/L/mg vs 4.0 nmol/L/mg). Smokers got higher prescribed (P < 0.05) doses of OLA than nonsmokers did. In the group with reported side effects, the median serum OLA concentration was 22% higher (P < 0.05) than in the group without side effects. Patients co-medicated with carbamazepine had a 71% lower median C/D ratio for OLA than patients on OLA monotherapy. The present TDM-based follow-up suggests that the influence of gender, smoking habits, and certain drug interactions may need to be considered for optimal dosage of OLA. TDM may be used for this purpose more readily in the future.

Postmortem samples from individuals with schizophrenia (n = 13) and control subjects (n = 10) were investigated for binding of [3H]tiagabine to GABA transporter-1 GAT-1. The binding was analyzed in the cingulate cortex and the caudate nucleus. There were no differences in binding affinity between the groups in any of the investigated areas. The maximum number of binding sites (Bmax) was elevated in the schizophrenic cingulate cortex compared to controls (1,264 ▒ 96 vs. 860 ▒ 123 fmol/mg of protein). The Bmax in the caudate nucleus for schizophrenics (426 ▒ 40 fmol/mg of protein) was the same as for controls (495 ▒ 69 fmol/mg of protein). The increase in GAT-1 in schizophrenia could be explained by a modulatory upregulation in the cingulate cortex. Copyright ⌐ 2002 S. Karger AG, Basel.